Combined fuse bank and alarm switch



July 12,1949.

A. BUCKLEY COMBINED FUSE BANK AND ALARM SWITCH 3 Sheets-Sheet 1 FiledJan. 8, 1948 July 12, 1949. A. H. BUCKLEY COMBINED FUSE BANK AND ALARMSWITCH 5 Sheets-Sheet 2 Filed Jan. 8, 1948 7' git/{514a Z9. (1y. 5M WJuly 12, 1949. A. H. BUCKLEY COMBINED FUSE BANK AND ALARM SWITCH 3Sheets-Sheet 3 Filed Jan. 8, 1948 Patented July 12, 1949 COMBINED FUSEBANK AND ALARM SWITCH Arthur H. Buckley,

Chicago, 111., assignor to Reliable Electric Company, Chicago, 111., acorporation of Illinois Application January 8, 1948, Serial No. 1,207

Claims.

This invention relates to alarm systems, and more particularly to analarm system for directing attention to the location of an opencircuited fuse that is one of perhaps thousands of fuses in a centralinstallation.

As is well known, the central office equipment in communication andother electrical systems includes a large number of separate electricalcircuits, and each one of these circuits normally requires an overloadprotective device. These protective devices generally take the form ofthermal fuses that contain current carrying fuse metal having acomparativel low temperature melting point. When more than apredetermined amount of current passes through the fuse metal, thetemperature generated therein is sufficient to melt the metal and thusopen the circuit before damage is done to other circuit components.

Where perhaps thousands of such fuses are closely arranged in what arecalled fuse banks, it is desirable to provide an alarm system fordirecting attention to the location of a particular open circuited fuse.

Accordingly, one object of the invention is to provide an alarm systemhaving characteristics such that it can be relied upon to operate at allneeded times, particularly at times that may be months or even yearsafter the installation of the alarm system. Therefore, the inventioncontemplates features intended to obviate operational difliculties thatsometimes occur with infrequently used mechanical and electricalapparatus.

Another object permits the use of precious metal electrical contacts inthe switches used with the alarm system. Since the cost of such metalcontacts would be prohibitive if a pair of such contacts were used witheach individual circuit, the advantages thereof without the prohibitivecosts are achieved through the use of a single pair of contacts with aplurality of separate circuits.

Still another object contemplates an alarm system for use with a largenumber of fuse banks, the indicator components of the system taking theform of a signal lamp associated with each one or two fuse banks, and anaudio indicator associated with each larger group of fuse banks. Withsuch indicators, an open circuited fuse in any one of the many fusebanks of the installation causes a buzzer or other suitable audio deviceto direct attention in the general direction of the alarm actuating,open circuited fuse. The signal lamp on the fuse bank containing theopen circuited fuse then directs attention to that particular fuse bank.Since the fuses used are of 2 the plunger type such as shown in UnitedStates Patent No. 1,691,705 to Wallace L. Cook, the particular opencircuited fuse in the indicated fuse bank is readily identifiable.

Other objects and advantages of the invention will become apparent asthe description proceeds, reference being had to the accompanyingdrawings wherein one form of the invention is shown. It is to beunderstood that the description and drawings are illustrative only, andare not to be taken as limiting the invention except insofar as it islimited by the claims.

In the drawings,

Fig. l is a view in side elevation of a fuse bank which the presentinvention has been applied; Fig. 2 is a view in front elevation of thefuse bank;

Fig. 3 is a top view of the fuse bank;

Fig. 4 is a sectional view on line 4-4 of Fig. 1;

Fig. 5 is an enlarged fragmentary view of a portion of Fig. 4 showingcertain mechanical components of the invention in alternative positions;

Fig. 6 is a view showing details of the switch mechanism connected incircuit with the indicaters to complete the circuit in response to anopen circuited fuse;

Fig. '7 is a circuit diagram suitable for use with the invention;

Fig. 8 is a view in side elevation, partly in section, showing detailsof the plunger type thermal fuses used with the invention;

Fig. 9 is a fragmentary view in front elevation of a fuse bank showingcertain details of the invention; and

Figs. 10 and 11 are views showing additional details of the switchmechanism of the invention.

Referring now to the drawings, a fuse bank of the type used with theinvention is generally indicated at I5. Fuse bank l5 may consist of avertically disposed structural member l6 that carries spaced brackets11. A central sheet l8 of insulatin material is associated with bracketsI1, and thus it is supported in a vertical plane by member l6.

Central sheet l8 carries a plurality of vertically spaced rear fuseholders 20 (Figs. 3 and 4) and a plurality of corresponding front fuseholders 2|. A fuse 22 is carried by each pair of corresponding front andrear fuse holders.

Thus it will be seen that each fuse bank l5 comprises in reality twosubsidiary banks of fuses, the two banks being disposed symmetricallyone on each side of central sheet 18. A fuse bank may contain anyconvenient number of vertically am ss metal, a spring 24 (Fig. 8) withinthe fuse body causes the plunger to eject to .thus provide a visualindication of fuse failure. Since plunger*23is ejected with some degreeofforce under the influence of spring 24, the action of the movingplunger is used in connection with a mechanical switch, presently to bedescribed, to cause operation of the present alarm system.

For convenience, the following description will concern itself with thefuse bank and associated instrumentalities lying on one side of centralsheet {8, it being understood that the structure'on the other side issymmetrical therewith. Operation of the present alarm system dependsupon a novel switch mechanism that is provided in conjunction with eachvertical bankof fuses, the switch being such that it is actuated by anyone-of the {uses of that bank. As mentioned, the switch is actuatedthrough action of the moving plunger of an overloaded fuse.

The switch mechanism comprises elongated member 26 that extends inspacedrelation to the front ends of the fuses in a bank. lhe elongatedmember 26 falls or is forced to asecondor lower to rotate through alimited arc through action of a plunger 23 following a fuse overload. nemeans for rotatably mounting member 26 takes the form of a Vertical rod21. that has itsupper and lower ends bent to provide horizontabportions28 and 29, respectively. 'I'heportions 28 and- 29 extend rearwardly ofthe front of the fuse bank and are suitably fastened to central sheetI8. Elongated member 26 has upper and lower horizontal lugs 30 and 31,respectively, -the lugs having holes therein through which the rod21pxtends. Thus rod 21 forms an axis of rotation for elongated member26, rotationot the member 26 through a limited arcof say'20 degreesoccurring as a result of plunger action. g

The vertical portion of rod- 211 is somewhat longer than elongatedmember- 26 so'that the latter may move through a limited vertical--distance along the length of rod 21. ;As will later be seen, themember 26 is normally in a first or upper axial position on'rod 21, andthenupon member 7 rotation following fuse overload the member 26 failsoris forced to a-secondior lower position. When the member is-in itslowerposition, the switch associated with the-member becomes closed, aswill presently be seen.

The axial movement of member 26 is permitted by a cam element 33 that-ispositionedbetween the bottom of member 26 and the horizontalportion 29of rod 21. As illustrated, cam'element 33 isintegral with the bottom ofmember 26, andit rests under the weight of member 26 on red portion 29.Element 33' is providedwith at least'one step in its cam surface so thatthe element supports member 26 in either oftwo vertical positions withrespect to rod .portion 29. One vertical position is illustrated inFig.;.6 wherein the edge 34 of cam element 33fis resting on portion 29.This position is the first or'upper position previously mentioned. Thesecond or'ilowerposition is brought about throughrotatiorfof member .26,

the cam element 33"being alsofota'tedso'that'the 4 step therein passesportion 29 and permits the member 26 to fall to the second or lowerposition shown in Figs. 10 and 11. In this position the horizontal plate35 of cam element 33 rests on the portion 29 of rod 21. Member 26 andcam element 33 constitute the actuating portions of the switchmechanism.

Referring-again to Figs 5,6, llland 1-1, the remaining portions of theswitch mechanism will 'now be described. A fuse bank identifying numberplate 38 is mounted at the bottom of central sheet IS. The number plate38 carries a laterally extending bracket39 having on its upper surface aswitch contactAD. The contact 40 desirably is madeofpalladium metal orother suitable precious metal having satisfactory characteristics foruse as'a'switch Contact. Cam element 33 has a laterally extendingportion 4| that carries on its bottom surface a switch-contact 42 madeof similar precious metal material.

The switch contacts"40 -and 42'areso disposed with respect to each otherthat they are in a spaced apart relationship when the member 26 is inits first or upper position. However, upon rotation of member 26 inresponseto'fuse action and the consequent movem'ent'of member 26 to itssecond or lower position, switch contact is brought to alignment with'switchcon'tact lfl' "so that the two contacts enter into physicalengagement, thus'closing thefsv'v'itch' ande s'tablishingthe circuit tothe indicatorcompon'ents of the alarm system.

Referring to Fig's.'2' and e, anfimport'ant feature of the abovedescribed switch actuating mechanism resides in the use" of tensiondspring 45. The purpose ofspring li isftofprovidea force betweenelongatedhiember '26 and a stationary part of the fuse "bank, desirablythe vertical rod 21' that 'forms'the support'and the axis of rotationfor member-26. As shownfone end of the spring isan'chored at apoint-46cm the top 'of member zsawaynom the-axis Iof rotation, while theother endof the"sp'r'ing .is anchored to a point 41'on' radar. "Thepoint in is located'in a position on rod 21 so that-the spring ends aredisposed in spacediradial planes when the member 26'is in its first orupper position. The angle between 'the radial planes passing through thespring ends -is roughly the angle throughwhic'h' member 26 rotatesinpassing to its second or lower position. Thus the spring is biased toassist in rotating member '26. L'Spring 45 is fixed'in an extendedcondition so that a force of tension continually exists between thepoints 46 and 41.

Spring '45 cooperates in-several different ways in influencing theaction of the switch mechanism. Firstly, when elongated member 26 is inits first or upperiposition (with .theswitch contacts out ofengagement), the spring causesa pressure relationshipbetween camsurface34' and the horizontal portion29 of rod 21. This ,pressure engagementtends tomaintain the member 26 in itsfirst' "angular position.againstaccidental or unwanted rotation 'such as might .occur throughvibrations or other causes. Secondly, due to the biased manner'in"which.spring'f4,5 is mounted, the "spring tension ."augmentsfthe"force applied to member 26 by -a projecting plunger 23, so as to insurethat"member' 26 rotates 'the necessary amount toimove into its second orlower position. As'will beunderstood, conditions of dust or rustoccurring over apefioaer timemi'ght adversely: afie'ctthe pivotalconnction between member 26 and the red 2150 that plunger avtion alonemight be insuificient to cause the necessary amount of rotation. Springinsures that suflicient rotation takes place. Thirdly, the forceprovided by spring 45 assists the action of gravity in overcoming anyresistance between member 26 and rod 21 so that the member 26 will bemoved to its second or lower position. Lastly, the tension of spring 45insures a pressure engagement between switch contacts 4!! and 42, thusproviding a satisfactory electrical connection between the two contacts.

Thus it is seen that spring 45 is of particular value in the switchactuating portion of the invention since it tends to overcome conditionsof dust, rust, etc. that are likely to occur over a period of time. Itis to be appreciated that months or even years might elapse before aparticular switch is actuated, and it is, of course, vitally importantthat the switch will properly operate whenever called upon to do so.

The foregoing fuse responsive switch is connected in circuit with theindicator components of the alarm system. One indicator component takesthe form of a signal lamp mounted on the top of each fuse bank l5. Eachfuse bank, in the equipment illustrated, comprises two symmetricalsubsidiary banks of fuses located one on each side of central sheet I8.Actuation of the switch associated with a particular fuse bank [5 causesillumination of the signal lamp 5B associated with that fuse bank.

The circuit diagram of Fig. 7 shows one possible manner in which theswitch mechanism may be connected in circuit with the indicatorcomponents of the invention. The input terminals to the circuit areindicated by the positive and negative symbols although, of course,alternating current could be used. The circuit including signal lamp 50may be traced from the positive input terminal through switch contacts40 and 42, lamp 59, the winding of a solenoid 5!, through an off-onswitch 52 to the negative input terminal. The ofi-on switch, of course,is in the on position when the alarm system is in condition for use.

The other indicator component of the alarm system is an audio devicesuch as a buzzer 54. The buzzer 54 is energized through a microswitch 55actuated by solenoid 5|. From Fig. '7 it will be seen that the coil ofsolenoid 5l is energized when the switch contacts 40 and 42 are broughtinto engagement. Upon solenoid actuation of microswitch 55, currentpasses from the positive input terminal through the microswitch tobuzzer 54, and from buzzer 54 through off-on switch 52 to the negativeinput terminal. It will be noted that the off-on switch 52 must be movedto its off position momentarily in order to de-energize solenoid 5| sothat spring 56 associated with microswitch 55 may break the connectionthrough switch 55 and thus de-energize buzzer 54. Referring again to themechanical switch mechanism associated with each fuse bank l5, it willbe seen that there is required only a slight manual movement of member26 in order to recondition the alarm system after an instance of use. Itis only necessary, following replacement of an overloaded fuse, toslightly raise member 26 and to rotate it so that it assumes its firstor upper position on the rod 27. This movement separates switch contacts40 and 42 and thus conditions the alarm system for subsequent use.

From the above description it is thought that the construction andadvantages of this invention will be readily apparent to those skilledin the art.

Various changes and modifications may be made without departing from thespirit or losing the advantages of the invention.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent is:

1. In combination with a fuse bank containing plunger type thermalfuses, a switch for energizing an alarm system for directing attentionto the location of an open circuited fuse, said switch comprising anelongated member disposed in effective relation with the plungers ofsaid fuses, a first switch contact on said elongated member, a secondswitch contact on said bank, said member being mounted for rotation andbeing rotatable upon engagement by the plunger of an open circuitedfuse, said member also being movable along its axis of rotation, a camelement operable upon member rotation to permit axial movement of saidmember whereby said switch contacts may be moved from a spaced relationto a contacting relation, and a spring exerting pressure between saidmember and a point on said fuse bank whereby said spring cooperates inrotating said member, in causing axial movement thereof and inmaintaining a pressure engagement between said switch contacts.

2. In combination with a fuse bank containing plunger type thermalfuses, a switch for energizing an alarm system for directing attentionto the location of an open circuited fuse, said switch comprising anelongated member disposed in effective relation with the plungers ofsaid fuses, a first switch contact on said elongated member, a secondswitch contact on said bank, said member being mounted for rotation andbeing rotatable upon engagement by the plunger of an open circuitedfuse, said member also being movable along its axis of rotation, meansfor maintaining said member in an axial position with a space betweensaid switch contacts, and means permitting axial movement of said memberwhen said member is rotated by engagement therewith of the plunger of anopen circuited fuse whereby said switch contacts are brought intoengagement.

3. In combination with a fuse bank containing plunger type thermalfuses, a switch for energizing an alarm system for directing attentionto the location of an open circuited fuse, said switch including avertical rod extending in spaced relation with the plungers of saidfuses, said rod having a horizontal portion at its lower end connectedto said fuse bank, an elongated member having lugs that engage said rodwhereby said member is rotatable about said rod upon engagement by theplunger of an open circuited fuse, a cam element associated with saidmember and the horizontal portion of said rod for normally holding saidmember in a first position, said cam element having a step therein thatcooperates upon rotation of said member to permit said member to assumea second position, switch contacts that are spaced apart when saidmember is in first position and are in engagement when said member is insecond position, and a spring exerting pressure between said member andsaid rod whereby said spring cooperates to maintain said member in firstposition, to effect rotation of said member following plungerengagement,

' to move said member to its second position and to maintain pressureengagement between said switch contacts.

4. In combination with a fuse bank containing plunger type thermalfuses, a switch for energizing an alarm system for directing attentionto ans-gees the location-of an open r circu'ited fuse,1said switchcomprising i-an elongated member ::disposed in effective relation withthe plungersiof. said fuses, a first sw'itch contact on-said:elongatedmember, a second switch :contact on said bank; said member being mountedfor longitudinal movement, means permitting longitudinal movement otsaid member upon engagemenhof said member by the plunger-of an opencircuitedt fuse, :and -a spring exerting -pressure between saidmember-and said bank whereby said spring 'coopera'tes i @to. insurelongitudinal movement of said -m'ember upon plunger I action :andconsequent. closure of said switch' contacts.

--5.- In combination-with a fuse bank containing plunger type thermalfuses a switch for energizing an"a1arm system' 'for-rzdirectingattention to theiocation of an open circuited fuse, said-switchcemprisingian elongated umember disposed in effective relation withthe=p1ungers=of said fuses,

a fi'rst switch contact-on said elongated :memb'er,

a second sootclrcontactlomsaid saidimemher 1 being mountedtori-ilnngitudinalamovement. means permittmgidongiiaudinahmovementzof:said member upon engagement: 'ofissaid membemby-the plungerofitaneiopenmircuited arise; whereby-etc effectr'closures ofsaidsswitch: contacts.

. iREEERENGES :GITED The following references are on-record in the fileof this. patent:

